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A carbon nanotube transistor array was used to detect DNA hybridization. A new approach to ensure specific adsorption of DNA to the nanotubes was developed. The polymer poly (methylmethacrylate(0.6)-co-poly(ethyleneglycol)methacrylate(0.15)-co-N-succinimidyl methacrylate(0.25)) was synthesized and bonded noncovalently to the nanotube. Aminated single-strand DNA was then attached covalently to the polymer. After hybridization, statistically significant changes were observed in key transistor parameters. Hybridized DNA traps both electrons and holes, possibly caused by the charge-trapping nature of the base pairs.

A highly efficient room‐temperature synthetic route to bioconjugable polymeric nanoparticles in the 5–20 nm size range based on single‐chain intramolecular click cycloaddition is described. It is illustrated by preparing single‐chain cross‐linked polymeric NPs from poly[MMA‐co‐(3‐azidopropyl methacrylate)‐co‐(3‐trimethylsilyl‐propyn‐1‐yl methacrylate)] terpolymers using a one‐pot procedure and a continuous addition technique. For polymeric NPs with an excess of azide groups, aminoacid/PMMA NPs were easily obtained by performing a second click reaction with propargyl glycine. This versatile and general method opens the way to the synthesis of other kinds of polymeric and bioconjugated NPs beyond those reported in this communication.magnified image

The synthesis of polymer nanoparticles (NPs) with controlled characteristics has become an appealing research topic lately. Nanomedicine, and especially drug delivery and imaging, are fields that require particles of a controlled size and with a tailored arrangement of functional groups. Intramolecular cross-linking or collapse of single polymer chains has emerged as an efficient alternative for the synthesis of well-defined polymer NPs. This technique allows the generation of 1.5-20 nm particles with a wide variety of chemical compositions and functionalities. This review begins by gathering synthetic strategies described in the literature and groups them into four main synthetic methods: homo-functional collapse, hetero-functional collapse, crosslinker-mediated collapse, and one-block collapse of diblock or triblock copolymers. Afterwards, the main characterization techniques and physical properties of single-chain polymer NPs (SCPNs) are exposed. Finally, several applications in nanomedicine are mentioned followed by some future perspectives.

Despite numerous strategies involving dynamic covalent bonds to produce self-healing hydrogels with similar frequency-dependent stiffness to native tissues, it remains challenging to use biologically relevant thiol/disulfide exchange to confer such properties to polymeric networks. Herein, we report a new method based on Metal(I) [Au(I) or Ag(I)] capping to protect thiolates from aerial oxidation without preventing thiolate/disulfide exchange. Dynamic hydrogels were readily prepared by injecting simultaneously aqueous solutions of commercially available HAuCl4 and 4-arm thiol-terminated polyethylene glycol [(PEGSH)4], resulting in a network containing a mixture of Au(I)-thiolate (Au-S) and disulfide bonds (SS). While the dynamic properties of the hydrogel were closely dependent on the pH, the mechanical properties could be easily tuned by adjusting (PEGSH)4 concentration and amount of Au-S, as judged by dynamic rheology studies. Permanent Au-S/SS exchange at physiological pH conferred self-healing behavior and frequency-dependent stiffness to the hydrogel. In addition, in vitro studies confirmed that Au-based dynamic material was not cytotoxic to human dermal fibroblasts, demonstrating its potential use as a medical device. Dynamic hydrogels obtained using Ag(I) ions demonstrated that the exchange reaction was not affected by the nature of the Metal(I) capping. Finally, this efficient thiolate capping strategy offers a simple way to produce injectable and self-healing dynamic hydrogels from virtually any thiol-containing polymers.

The ability of gold(I) thiolates to self-assemble into polymeric species has been exploited to create a pH responsive supramolecular hydrogel based on glutathione.

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The development of sensors to detect specific weak biological interactions is still today a challenging topic. Characteristics of carbohydrate-protein (lectin) interactions include high specificity and low affinity. This work describes the development of nanostructured impedimetric sensors for the detection of concanavalin A (Con A) binding to immobilized thiolated carbohydrate derivatives (D-mannose or D-glucose) onto screen-printed carbon electrodes (SPCEs) modified with gold nanoparticles. Thiolated D-galactose derivative was employed as negative control to evaluate the selectivity of the proposed methodology. After binding the thiolated carbohydrate to the nanostructured SPCEs, different functionalized thiols were employed to form mixed self-assembled monolayers (SAM). Electrochemical impedance spectroscopy (EIS) was employed as a technique to evaluate the binding of Con A to selected carbohydrates through the increase of electron transfer resistance of the ferri/ferrocyanide redox probe at the differently SAM modified electrodes. Different variables of the assay protocol were studied in order to optimize the sensor performance. Selective Con A determinations were only achieved by the formation of mixed SAMs with adequate functionalized thiols. Important differences were obtained depending on the chain lengths and functional groups of these thiols. For the 3-mercapto-1-propanesulfonate mixed SAMs, the electron transfer resistance varied linearly with the Con A concentration in the 2.2-40.0 μg mL(-1) range for D-mannose and D-glucose modified sensors. Low detection limits (0.099 and 0.078 pmol) and good reproducibility (6.9 and 6.1%, n=10) were obtained for the D-glucose and D-mannose modified sensors, respectively, without any amplification strategy.